Semiconductor device and a method of manufacturing the same

ABSTRACT

A semiconductor device manufacturing technique which allows reduction of semiconductor chip size. First, a pad and other wires are formed over an insulating film. A surface protective film is formed over the insulating film including the pad and wires, and an opening is made in the surface protective film. The opening lies over the pad and exposes a surface of the pad. A bump electrode is formed over the surface protective film including the opening. Here, the pad is smaller than the bump electrode. Consequently, the wires are arranged just beneath the bump electrode in the same layer as the pad 10. In other words, the wires are arranged in space which becomes available because the pad is small enough.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device and a method ofmanufacturing the same and more particularly to a technique which isuseful for semiconductor devices used in LCD (Liquid Crystal Display)drivers.

Japanese Unexamined Patent Publication No. Hei 10 (1995)-233507discloses a technique which reduces the chip area and achievesproduction efficiency improvement and cost reduction regardingsemiconductor integrated circuits such as driver ICs with many outputpads and electronic circuit devices such as electronic clocks.

Concretely, an output pads is placed over a drive transistor to beconnected with the output pad or over a logic circuit so that theyoverlap each other as seen in a plan view. Furthermore, not onlyaluminum wires but also bump electrodes or barrier metals are used forsemiconductor device wiring interconnection. Also, in a case that asemiconductor integrated circuit is electrically bonded over a printedcircuit board face down, electrical connections are made by directlyconnecting solder bumps of the semiconductor integrated circuit withwires of the printed circuit board. In this case, bump electrodes asexternal connection terminals for the semiconductor integrated circuitare stacked over transistors.

For example, FIG. 18 of the above patent document shows that a bumpoutput pad lies over a drive transistor. Hence, since the drivetransistor and the output pad overlap as seen in a plan view, the chiparea can be reduced. Furthermore, FIG. 26 of the document shows that onediffusion area and another diffusion area are electrically connected bybump interconnection. This structure makes it possible to have one morewiring layer as compared with the conventional structure.

SUMMARY OF THE INVENTION

In recent years, LCDs which use liquid crystal for display devices havebeen spreading rapidly. These LCDs are controlled by drivers which drivethem. An LCD driver comprises a semiconductor chip, which is typicallymounted on a glass substrate. The semiconductor chip which constitutesthe LCD driver has a structure that plural transistors and multilayerinterconnections are formed over a semiconductor substrate with bumpelectrodes on its surface. The chip is mounted over the glass substratethrough the bump electrodes formed on the surface. Here, thesemiconductor chip and the glass substrate are connected through thebump electrodes. For the purpose of increasing the adhesive force, thebump electrode area is enlarged to increase the area of contact betweenthe semiconductor chip and the glass substrate. In other words, bumpelectrodes of a semiconductor chip which constitutes an LCD driver aremuch larger than bump electrodes of semiconductor chips for generalpurposes.

In an LCD driver, an insulating film which functions as a passivationfilm is formed under bump electrodes and connected with pads formed inthe top layer of the multilayer interconnection through openings in theinsulating film. Usually the area of an opening and the area of a padare determined according to the area of a bump electrode so that theyare almost equal.

As mentioned above, pads which match large bump electrodes are formed inthe top layer of the semiconductor chip multilayer interconnection. Morespecifically, pads which have almost the same area as the bumpelectrodes are formed in the top layer. This means that in order toleave space for forming interconnection wires different from pads in thetop layer of the multilayer interconnection, the semiconductor chip sizemust be larger.

Another problem is that in a normal structure in, which bump electrodesare formed just above bonding pads, the positions of bump electrodes arefixed and there are limitations about the layout arrangement of wiringelements such as pads. Consequently it is difficult to adopt a layoutarrangement which permits efficient reduction of semiconductor chipsize.

An object of the present invention is to provide a technique whichpermits reduction of semiconductor chip size.

Another object of the invention is to provide a technique which permitsgreater latitude in the layout arrangement of interconnection wiresformed in the semiconductor chip.

The above and further objects and novel features of the invention willbecome more apparent from the following detailed description in thisspecification and the accompanying drawings.

Preferred embodiments of the invention which will be disclosed hereinare briefly outlined below.

According to one aspect of the present invention, a semiconductor deviceincludes a semiconductor chip which comprises: (a) a pad formed over asemiconductor substrate; (b) an insulating film having an opening overthe pad; and (c) a bump electrode formed over the insulating filmincluding the opening. Here, the bump electrode is larger than the pad;and a wire different from the pad is formed in a layer under the bumpelectrode through the insulating film.

According to another aspect of the invention, a semiconductor deviceincludes a semiconductor chip which comprises: (a) a pad formed over asemiconductor substrate; (b) an insulating film having an opening overthe pad; and (c) a bump electrode formed over the insulating filmincluding the opening. Here, the bump electrode is larger than the pad;and the bump electrode includes a first portion with a small width and asecond portion with a width larger than the width of the first portion.

According to a further aspect of the invention, a method ofmanufacturing a semiconductor device comprises the steps of: (a)forming, in a layer over a semiconductor substrate, a pad and a wirewhich is different from the pad; (b) forming an insulating film over thepad and the wire different from the pad; (c) making an opening in theinsulating film to expose a surface of the pad; and (d) forming a bumpelectrode over the insulating film including the opening. Here the padand the wire different from the pad are formed in a layer under the bumpelectrode through the insulating film.

According to a further aspect of the invention, a method ofmanufacturing a semiconductor device comprises the steps of (a) forminga pad over a semiconductor substrate and (b) forming an insulating filmover the pad. It further comprises the steps of (c) making an opening inthe insulating film to expose a surface of the pad and (d) forming abump electrode over the insulating film including the opening. Here thebump electrode includes a first portion with a small width and a secondportion with a width larger than the width of the first portion.

The effect brought about by preferred embodiments of the presentinvention is briefly described below.

The space beneath a bump electrode can be used effectively and thesemiconductor chip size can be reduced. Pads can be arranged regardlessof bump electrode positions, which permits greater latitude in thelayout arrangement of interconnection wires including pads.

BRIEF DESCRIPTION OF THE. DRAWINGS

The invention will be more particularly described with reference to theaccompanying drawings, in which:

FIG. 1 is a plan view of a semiconductor chip according to a firstembodiment of the present invention;

FIG. 2 is a sectional view taken along the line A-A′ of FIG. 1.

FIG. 3 is a sectional view taken along the line B-B′ of FIG. 1;

FIG. 4 is an enlarged plan view of a region as indicated by line C ofFIG. 1 showing that wires are formed just beneath linearly arranged bumpelectrodes;

FIG. 5 is an enlarged plan view of a region as indicated by line D ofFIG. 1 showing that wires are formed just beneath bump electrodesarranged in a zigzag pattern;

FIG. 6 is a sectional view showing a step in a semiconductor devicemanufacturing process according to the first embodiment;

FIG. 7 is a sectional view showing a step next to the step of FIG. 6 inthe semiconductor device manufacturing process;

FIG. 8 is a sectional view showing a step next to the step of FIG. 7 inthe semiconductor device manufacturing process;

FIG. 9 is a sectional view showing a step next to the step of FIG. 8 inthe semiconductor device manufacturing process;

FIG. 10 is a sectional view showing a step next to the step of FIG. 9 inthe semiconductor device manufacturing process;

FIG. 11 is a sectional view showing a step next to the step of FIG. 10in the semiconductor device manufacturing process;

FIG. 12 shows that a semiconductor chip is mounted on a glass substrate;

FIG. 13 is an enlarged view of the semiconductor chip mounted on theglass substrate;

FIG. 14 shows the general structure of an LCD;

FIG. 15 shows the general structure of another type of LCD;

FIG. 16 shows how a semiconductor chip is mounted on a packagingsubstrate in the TCP (Tape Carrier Package) form;

FIG. 17 shows an example in which a semiconductor chip packaged in theTCP form lies between a glass substrate and a printed circuit board;

FIG. 18 shows how a semiconductor chip is mounted on a packagingsubstrate in the COF (Chip On Film) form;

FIG. 19 shows an example in which a semiconductor chip packaged in theCOF form lies between a glass substrate and a printed circuit board;

FIG. 20 is a fragmentary plan view of a semiconductor chip according toa second embodiment of the invention;

FIG. 21 is a plan view showing a variation of the second embodiment; and

FIG. 22 is a plan view showing another variation of the secondembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments described below will be described separatelyas necessary, but they are not irrelevant to each other unless otherwisespecified. They are, in whole or in part, variations of each other andsometimes one description is a detailed or supplementary form ofanother.

Also, in the preferred embodiments described below, even when thenumerical datum for an element (the number of pieces, numerical value,quantity, range, etc.) is indicated by a specific numerical figure, itis not limited to the indicated specific numerical figure unlessotherwise specified or theoretically limited to the specific numericalfigure; it may be larger or smaller than the specific numerical figure.

In the preferred embodiments described below, it is needles to say thattheir constituent elements (including constituent steps) are notnecessarily essential unless otherwise specified or consideredtheoretically essential.

Similarly, in the preferred embodiments described below, when a specificform or positional relation is indicated for an element, it should beinterpreted to include forms or positional relations which are virtuallyequivalent or similar to the specific one unless otherwise specified orunless only the specific one should be used from a theoreticalviewpoint. The same can be said of numerical values or ranges asmentioned above.

Next, preferred embodiments of the present invention will be describedin detail referring to the accompanying drawings. In all the drawingsthat illustrate the preferred embodiments, elements with like functionsare basically designated by like reference numerals and repeateddescriptions thereof are omitted.

First Embodiment

FIG. 1 is a plan view showing the structure of a semiconductor chip 1(semiconductor device) according to the first embodiment. Thesemiconductor chip 1 according to the first embodiment is a driver foran LCD. Referring to FIG. 1, the semiconductor chip 1 has asemiconductor substrate 2 which takes the form of, for example, anelongated rectangle, and for example, an LCD driver which drives aliquid crystal display is formed on its main surface. This driver hasthe function of controlling the orientations of liquid crystal moleculesby supplying voltage to each pixel in a cell array constituting the LCDand includes gate drive circuits 3, a source drive circuit 4, a liquidcrystal circuit 5, graphic RAMs (Random Access Memories) 6, andperipheral circuits 7.

In the vicinity of the periphery of the semiconductor chip 1, aplurality of bump electrodes 8 are arranged at regular intervals alongthe periphery of the semiconductor chip 1. These bump electrodes 8 lieover active regions where elements and interconnection wires of thesemiconductor chip 1 are located. The plural bump electrodes 8 includebump electrodes for integrated circuits which are necessary for anintegrated circuit configuration and dummy electrodes which are notnecessary for the integrated circuit configuration. Bump electrodes 8are arranged in a zigzag pattern in the vicinities of one long edge andthe two short edges of the semiconductor chip 1. The plural bumpelectrodes 8 arranged in a zigzag pattern are mainly used as bumpelectrodes for gate output signals or source output signals. The bumpelectrodes 8 arranged in a zigzag pattern around the center of the longedge of the semiconductor chip 1 are bump electrodes for source outputsignals and those arranged in a zigzag pattern along the long edge ofthe semiconductor chip 1 in the vicinities of its corners and thosearranged in a zigzag pattern along the short edges of the semiconductorchip 1 are bump electrodes for gate output signals. This zigzag patternallows arrangement of many bump electrodes necessary for gate outputsignals and source output signals while eliminating the need forincrease in the size of the semiconductor chip 1. In other words, it ispossible to reduce the chip size and increase the number of bumpelectrodes at the same time.

In the vicinity of the other long edge of the semiconductor chip 1, bumpelectrodes 8 are arranged not in a zigzag pattern but linearly. Thelinearly arranged bump electrodes 8 are bump electrodes for digitalinput signals or analog input signals. Also dummy bump electrodes arearranged around the four corners of the semiconductor chip 1. In theexample shown in FIG. 1, bump electrodes 8 for gate output signals orsource output signals are arranged in a zigzag pattern and bumpelectrodes 8 for digital input signals or analog input signals arearranged linearly. However it is also possible that bump electrodes 8for gate output signals or source output signals are arranged linearlyand bump electrodes 8 for digital input signals or analog input signalsare arranged in a zigzag pattern.

FIG. 2 is a sectional view taken along the line A-A′ of FIG. 1. In FIG.2, the layers under the top layer are omitted. Although not shown inFIG. 2, a semiconductor element such as a MTSFET (Metal InsulatorSemiconductor Field Effect Transistor) is formed over the semiconductorsubstrate and a multilayer interconnection is made over thesemiconductor element. FIG. 2 shows the multilayer interconnection abovethe top layer of the multilayer interconnection structure.

As shown in FIG. 2, top layer interconnection wiring is made over theinsulating film 9 of, for example, oxide silicon. The top layerinterconnection wiring includes, for example, a pad 10 and wiresdifferent from the pad 10, 11 a and 11 b. The wires 11 a and 11 b are,for example, signal wires for signals or power wires for power supply ordummy wires. The pad 10 and wires 11 a and 11 b consist of, for example,an aluminum film.

A surface protective film (passivation film) 12 is formed over the pad10 and wires 11 a and 11 b so as to cover the pad and wires 11 a and 11b. For example, the surface protective film 12 consists of an insulatingfilm of silicon nitride. An opening 13 is made in the surface protectivefilm 12 to expose a surface of the pad 10 and a bump electrode 8 isformed over the surface protective film 12 including the inside of theopening 13 through a UBM film 14 as an undercoat metal film.

Under the bump electrode 8 are the wiring layer including the pad 10 andwires 11 a, 11 b, and plural other wiring layers (not shown) lying underthe wiring layer including the pad 10 and wires 11 a, 11 b. Similarly, asemiconductor element such as the abovementioned MISFET (not shown) isformed under the bump electrode 8. Thus, this embodiment makes itpossible to reduce the chip area of the semiconductor chip 1 byefficient use of space under the bump electrode 8.

One characteristic point of the present invention is that the opening 13and the pad 10 are smaller than the bump electrode 8. Conventionally anopening 13 whose size is almost equal to the bump electrode 8 has beenformed under the bump electrode 8 and a pad 10 larger than the bumpelectrode 8 has been formed under the opening 13. In other words, thepad 10 has been formed under the bump electrode 8 and the size of thepad 10 has been almost the same as the size of the bump electrode 8.However, in the semiconductor chip 1 which constitutes an LCD driver,the bump electrode 8 should be enlarged in order to ensure its adhesionto the glass substrate. Hence, the pad 10 which is formed in a layerunder the bump electrode 8 should be larger. If the pad 10 is too large,it would be difficult to leave space for wires different from the pad 10in the top layer of the multilayer interconnection and as a consequencethe size of the semiconductor chip 1 would have to be increased. On theother hand, in this first embodiment, the opening 13 and the pad 10 aresmaller than the bump electrode 8 as shown in FIG. 2. Put another way,the bump electrode 8 is larger than the pad 10. When the pad 10 issmaller than the bump electrode 8 in this way, space is left for wiresdifferent from the pad 10, 11 a and 11 b, in a layer under the bumpelectrode 8. This may be put as follows. In the conventional structure,because the pad 10 lies in the top layer just beneath the bump electrode8, it has been impossible to make other wires in the same top layer. Onthe other hand, in the first embodiment, since the pad 10 is smallerthan the bump electrode 8, space available for formation of other wires11 a and 11 b is left just beneath the bump electrode 8 in the same toplayer in which the pad 10 lies. Therefore, it is possible to form wires11 a and 11 b just beneath the bump electrode 8 in addition to the pad10, so that space just beneath the bump electrode 8 can be usedeffectively and the size of the semiconductor chip 1 can be reduced.

The first embodiment is characterized in that the size of the bumpelectrode 8 remains unchanged and the pad 10 is smaller than the bumpelectrode 8, leaving space for formation of wires different from the pad10 for the bump electrode 8. In sum, while the area of the bumpelectrode 8 to adhere to the glass substrate is large enough, space forwires different from the pad 10 is left so that the size of thesemiconductor chip 1 can be reduced. This technical idea is notdescribed nor suggested even in the patent document cited earlier underthe heading “BACKGROUND OF THE INVENTION” and unique to this firstembodiment. For example, it is possible to make the bump electrodelarger than the pad by increasing the size of the bump electrode withoutchanging the pad size; however, in this case, the size of the pad itselfis not reduced and space left by reducing the pad size cannot beobtained. Consequently the size of the semiconductor chip cannot bereduced. Besides, a larger bump electrode leads to a largersemiconductor chip, which means that it is impossible to reduce the sizeof the semiconductor chip. As discussed above, there are two approachesto realizing a pad electrode smaller than a bump electrode: one is toincrease the size of the bump electrode and the other is to reduce thesize of the pad. These two approaches are the same in that the padelectrode is smaller than the bump electrode but the approach in whichthe pad size is reduced is considerably different from the otherapproach in that space for wires different from the pad is left underthe bump electrode in the same layer in which the pad lies. In addition,since the size of the pad itself is reduced, the pad width may besmaller than a relatively wide wire different from the pad, such as apower wire.

FIG. 3 is a sectional view taken along the line B-B′ of FIG. 1. As shownin FIG. 3, in the cross section taken along the line B-B′, a pad 10 isformed over the insulating film 9 and a surface protective film 12 isformed so as to cover the pad 10. An opening 13 is made in the surfaceprotective film 12 and a surface of the pad 10 is exposed at the bottomof the opening 13. A bump electrode 8 is formed over the surfaceprotective film 12 including the inside of the opening 13 through a UBMfilm 14. In the direction of the cross section taken along the lineB-B′, the width of the pad 10 is almost equal to, or larger than, thewidth of the bump electrode 8. In other words, in the direction of thecross section taken along the line A-A′ of FIG. 2, the width of the pad10 is smaller than the width of the bump electrode 8, and the pad 10 andother signal wires and power wires are formed just beneath the bumpelectrode 8. On the other hand, in the direction of the cross sectiontaken along the line B-B′ of FIG. 3, the width of the pad 10 formed justbeneath the bump electrode 8 is almost equal to that of the bumpelectrode 8.

FIG. 4 is an enlarged plan view of region C of FIG. 1 showing that wiresare formed just beneath linearly arranged bump electrodes 8. As shown inFIG. 4, rectangular bump electrodes 8 lie side by side along the shortedge direction (perpendicular to the long edge direction). A surfaceprotective film 12 is formed under the bump electrodes 8 and openings 13are made in the surface protective film 12. A pad 10 is formed in alayer under the opening 13 made in the surface protective film 12. Thepad 10 is electrically connected with a bump electrode 8 partiallyburied in the opening. The pad 10 is square and one edge thereof isslightly longer than the short edge of the bump electrode 8.Consequently as shown in FIG. 4, the length of the pad 10 is slightlylarger than the length of the bump electrode 8 in the short edgedirection of the bump electrode 8. On the other hand, the length of thepad 10 is far smaller than the length of the bump electrode 8 in thelong edge direction of the bump electrode 8. Specifically, the pad 10 issmaller than the bump electrode 8 and the pad 10 lies only under one endof the bump electrode 8. Therefore, in the long edge direction of thebump electrode 8, space is left in the same wiring layer in which thepad 10 lies. Wires lla to 11 c which are different from the pad 10 areformed in this space. According to the first embodiment, as mentionedabove, wires 11 a to 11 c can be formed just beneath the bump electrode8 in the same layer in which the pad 10 lies. Since space just beneaththe rectangular large bump electrode 8 can be used effectively, the sizeof the semiconductor chip can be reduced.

The wires 11 a to 11 c are signal wires, power wires or dummy wires andmay have different widths. FIG. 4 indicates that the wire 11 c is widerthan the wires 11 a and 11 b. Conventionally the pad size has beensimilar to the size of the bump electrode 8 and the pad width isrelatively large as compared with other wires. On the other hand, inthis first embodiment, the pad 10 is smaller than the bump electrode 8and space available for formation of wires is left just beneath the bumpelectrode 8. Therefore, the width of the pad 10 may be smaller than, forexample, the width of a power wire formed in the abovementioned space.Thus, according to the first embodiment, the width of the pad 10 may besmaller than the width of another wire.

The wires 11 a to 11 c extend along the direction perpendicular to thelong edge direction of the bump electrode 8. Although it is desirablefrom the viewpoint of effective use of space that the wires 11 a to 11 cshould be perpendicular to the long edge direction of the bumpelectrodes 8, they need not necessarily be perpendicular to the longedge direction of the bump electrodes 8. For example, the wires mayobliquely intersect with the long edges of the bump electrodes 8depending on the interconnection pattern. Even if that is the case,space just beneath the bump electrode 8 is available and thesemiconductor chip can be smaller.

FIG. 5 is an enlarged plan view of region D of FIG. 1 showing that wireslie just beneath bump electrodes 8 arranged in a zigzag pattern. Asshown in FIG. 5, as in FIG. 4, in the long edge direction of the bumpelectrode 8, the width of the bump electrode 8 is far larger than thewidth of the pad 10, and space is left in the long edge direction of thebump electrode 8 in the same layer in which the pad 10 lies. Wires 11 dto 11 k are formed in this space. When bump electrodes 8 are arranged ina zigzag pattern, they form two rows as shown in FIG. 5. Therefore,space left just beneath bump electrodes 8 is larger than when bumpelectrodes 8 form one row. This means that if a pad whose size issimilar to the size of a bump electrode 8 is formed, it would beimpossible to form other wires in addition to the pad just beneath thebump electrode 8. In this case, when bump electrodes 8 are arranged in azigzag pattern, which means they are arranged in two rows, spaceavailable for formation of wires would be smaller than when bumpelectrodes 8 are arranged in one row. However, as shown in FIG. 5, inthe first embodiment, wires 11 d to 11 g are formed just beneath thebump electrodes 8 in the first row and wires 11 h to 11 k are formedjust beneath the bump electrodes 8 in the second row. Therefore, evenwhen the bump electrodes 8 are arranged in a zigzag pattern, space justbeneath the bump electrodes 8 can be used almost as effectively as whenthey are arranged in one row. Regarding bump electrodes 8 of thesemiconductor chip, wires can be formed not only beneath bump electrodes8 arranged in one row but also beneath the ones in a zigzag pattern andthe semiconductor chip size can be thus reduced.

The number of bump electrodes 8 in region D of FIG. 1 (FIG. 5) is largerthan in region C of FIG. 1 (FIG. 4). This is because more bumpelectrodes 8 are needed in region D of FIG. 1 in order to drive elementsof an LCD screen area 20 (described later) as shown in FIG. 15. The bumpelectrodes 8 in region D of FIG. 1 are mainly used for gates and sourcesof elements of the LCD screen area 20.

Next, the method of manufacturing a semiconductor device according tothe first embodiment will be described referring to the accompanyingdrawings. A semiconductor element such as a MISFET is formed over, forexample, a semiconductor substrate of silicon single crystal, and amultilayer interconnection is made over the semiconductor element,though not shown. FIG. 6 shows wires formed in the top layer where thelayers under the wires in the top layer are omitted.

For example, an insulating film 9 of oxide silicon is formed as shown inFIG. 6. The insulating film 9 may be formed using a CVD (Chemical VaporDeposition) process. A titanium or titanium nitride film, an aluminumfilm and a titanium or titanium nitride film are stacked over theinsulating film 9. Then, patterning is done on the stacked films byphotolithography or etching and a pad 10 and wires 11 a and 11 b areformed by this patterning process. The pad 10 thus formed is smallerthan a bump electrode formed by a process which will be described later.The wires 11 a and 11 b are formed just beneath a bump electrode.

Next, as shown in FIG. 7, a surface protective film 12 is formed overthe insulating film 9 in which the pad 10 and wires 11 a and 11 b areformed. The surface protective film 12 consists of, for example, asilicon nitride film and is made by a CVD process. Next, an opening 13is made in the surface protective film 12 by photolithography oretching. This opening 13 lies over the pad 10 and exposes a surface ofthe pad 10. The opening 13 should be smaller than the pad 10.

Next, as shown in FIG. 8, a UBM (Under Bump Metal) film 14 is formedover the surface protective film 12 including the inside of the opening13. The UBM film 14 is made by sputtering and consists of a single filmof titanium, nickel, palladium, titanium-tungsten alloy, titaniumnitride or gold or a laminate of films of these materials. The UBM film14 has not only the function of improving the adhesion of the bumpelectrode 8 to the pad 10 and surface protective film 12 but also thebarrier function which suppresses or prevents movement of the metalelement of a conductive film 16 made by a subsequent process toward thewire 11 a, 11 b or the like, or movement of the metal element of thewire 11 a, 11 b or the like toward the conductive film 16. The plan viewsize of the UBM film 14 is larger than that of the opening 13 and almostequal to that of the conductive film 16.

Next, as shown in FIG. 9, after a resist film 15 is coated over the UBMfilm 14, patterning is done by exposure and development of the resistfilm 15. Patterning is done in a way not to leave the resist film 15 inthe bump electrode formation region. Then, as shown in FIG. 10, forexample, a gold film is formed as a conductive film 16 by plating. Then,as shown in FIG. 11, a bump electrode 8, consisting of a conductive film16 and a UBM film 14, is formed by removing the pattern resist film 15and the UBM film 14 portion covered by the resist film 15. Next,separate semiconductor chips are produced by dicing the semiconductorsubstrate.

According to the first embodiment, since the pad 10 formed just beneaththe bump electrode 8 is small, wires 11 a and 11 b can be formed beneaththe bump electrode 8. The pad 10 and the wires 11 a and 11 b can beformed in the same layer just beneath the bump electrode 8, so that thespace left just beneath the bump electrode 8 can be effectively used andthe semiconductor chip size can be reduced.

The method of manufacturing a semiconductor device according to thefirst embodiment is the same as conventional semiconductor devicemanufacturing methods except that patterning is done in a way to form,just beneath the bump electrode 8, the pad 10 and the wires 11 a and 11b which should 11 e in the same layer as the pad 10. Therefore, asemiconductor device according to the first embodiment is manufacturedwithout complicating the manufacturing process. This means that anadvantageous effect is achieved without any drastic change in themanufacturing process.

Next, a semiconductor chip produced as mentioned above is bonded to apackaging substrate. FIG. 12 shows a case that the semiconductor chip 1is mounted over a glass substrate 17 a (COG: Chip On Glass). As shown inFIG. 12, a glass substrate 17 b is mounted on the glass substrate 17 a,forming an LCD screen area. A semiconductor chip 1 as an LCD driver ismounted on the glass substrate 17 a in the vicinity of the LCD screenarea. The semiconductor chip 1 has bump electrodes 8 where the bumpelectrodes 8 are connected with terminals formed on the glass substrate17 a through anisotropic conductive film 19. The glass substrate 17 aand a flexible printed circuit 18 are also connected through theanisotropic conductive film 19. In the semiconductor chip 1 mounted onthe glass substrate 17 a in this way, a bump electrode 8 for output iselectrically connected with the LCD screen area and a bump electrode 8for input is connected with the flexible printed circuit board 18.

FIG. 13 is an enlarged view of the semiconductor chip 1 mounted on theglass substrate 17 a. As shown in FIG. 13, terminals 20 a lie over theglass substrate 17 a and bump electrodes 8 of the semiconductor chip 1are electrically connected with the terminals 20 a. Here, the bumpelectrodes 8 and the terminals 20 a are connected not directly butthrough the anisotropic conductive film 19.

FIG. 14 shows the general structure of the LCD. As shown in FIG. 14, theLCD screen area 20 lies over the glass substrate and an image appears onthe screen area 20. The semiconductor chip 1 as an LCD driver is mountedover the glass substrate in the vicinity of the screen area 20. Theflexible printed circuit board 18 is mounted in the vicinity of thesemiconductor chip 1 and the semiconductor chip 1 as a driver liesbetween the printed circuit board 18 and the LCD screen area 20. Thesemiconductor chip 1 may be mounted over the glass substrate 17 a inthis way.

So far, the process of mounting an LCD driver on a packaging substratehas been explained as an example of COG where a semiconductor chip 1 ismounted on the glass substrate 17 a. Next, other forms of process ofpackaging semiconductor chips 1 will be explained.

FIG. 15 shows a TCP (Tape Carrier Package) form 21 and a COF (Chip OnFilm) form 22 as non-COG examples of semiconductor chip packaging. FIG.16 shows how a semiconductor chip 1 is mounted on a packaging substratein the TCP form. Referring to FIG. 16, the packaging substrate is a filmsubstrate in the tape form (tape substrate) 23 and for example, a leadwire of copper 24 is formed over the film substrate 23. Thesemiconductor chip 1 is mounted over the film substrate 23 so that abump electrode 8 adheres to the lead wire 24. The semiconductor chip 1is sealed with resin 25. FIG. 17 shows an example in which asemiconductor chip 1 packaged in the TCP form lies between the glasssubstrate 17 a and the printed circuit board 28. As illustrated in FIG.17, the glass substrate 17 a is connected with the lead wire 24 formedover the film substrate 23 through anisotropic conductive film 26 andsimilarly the lead wire 24 formed over the film substrate 23 isconnected with the printed circuit board 28 through anisotropicconductive film 27.

FIG. 18 shows how a semiconductor chip 1 is mounted on a packagingsubstrate in the COF form. Referring to FIG. 18, the packaging substrateis a film substrate 29 in the tape form. As in the TCP form, a lead wireof copper 30 lies over the film substrate 29 but unlike the TCP form,the lead wire 30 is fixed on the film substrate 29 even at the area ofconnection with a bump electrode 8. A semiconductor chip 1 is mountedover the film substrate 29 in a manner that the bump electrode 8 adheresto the lead wire 30. There is underfill 31 in the gap between thesemiconductor chip 1 and the film substrate 29. FIG. 19 shows an examplein which a semiconductor chip 1 is mounted between a glass substrate 17a and a printed circuit board 28 in the COF form. As illustrated in FIG.19, the glass substrate 17 a is connected with a lead wire 30 formedover a film substrate 29 through anisotropic conductive film 26 andsimilarly the lead wire 30 formed over the film substrate 29 isconnected with the printed circuit board 28 through anisotropicconductive film 27.

A semiconductor chip 1 as an LCD driver may be packaged in various formsas mentioned above.

Second Embodiment

The second embodiment concerns a semiconductor device with wide layoutlatitude which optimizes pad positions regardless of bump electrodepositions.

FIG. 20 is a fragmentary plan view of a semiconductor chip according tothe second embodiment. Referring to FIG. 20, a pad 10 is connected witha pad connection portion 8 a as a part of a bump electrode 8 through anopening 13 made in a surface protective film 12. The bump electrode 8consists of: a pad connection portion 8 a to be connected with the pad10; a terminal connection portion 8 c to be connected with a terminal ofa packaging substrate; and a wiring portion 8 b which connects the padconnection portion 8 a and the terminal connection portion 8 c. Aconventional bump electrode consists of only a terminal connectionportion which is connected with a pad. In other words, in a conventionalbump electrode, the terminal connection portion also functions as a padconnection portion, which means that the pad connection portion and theterminal connection portion overlap each other as seen in a plan view.On the other hand, in the bump electrode 8 according to the secondembodiment, the pad connection portion 8 a and the terminal connectionportion 8 c are formed in different places as seen in a plan view andthe pad connection portion 8 a and the terminal connection portion 8 cin different places as seen in a plan view are connected by the wiringportion 8 b. The pad connection portion 8 a and the terminal connectionportion 8 c are larger than the wiring portion 8 b in terms of wirewidth, as seen in a plan view. This is because the pad connectionportion 8 a and the terminal connection portion 8 c have to be connectedwith the pad 10 and the lead wire on the glass substrate (or filmsubstrate) respectively and therefore their flat surfaces must be largeenough to secure the connections. Since the wire width of the wiringportion 8 b is relatively small, contact with other wiring portions 8 bis less likely, permitting greater latitude in interconnection wiringarrangement.

Since each bump electrode 8 is thus structured, pads 10 can be arrangednot in a zigzag pattern but in one row in the X direction while terminalconnection portions 8 c of bump electrodes 8 are arranged in a zigzagpattern. This means that the positions of pads can be determinedregardless of the positions of bump electrodes. Conventionally, bumpelectrodes and pads overlap as seen in a plan view; and when bumpelectrodes are arranged in a zigzag pattern in the y direction, padsshould also be arranged in a zigzag pattern in the y direction. In thiscase, pads are arranged in two rows and wires different from the padscannot be laid in areas where the pads lie. Consequently, in this case,even when a pad is made smaller than a bump electrode in order to formwires different from a pad as mentioned above according to the firstembodiment, it would be impossible to increase space for formation ofwires different from pads because pads are formed in two rows in the ydirection. On the other hand, according to the second embodiment, evenwhen bump electrodes 8 are arranged in a zigzag pattern, pads 10 neednot be arranged in a zigzag pattern and can be arranged in one row inthe x direction as shown in FIG. 20. Therefore, space occupied by pads10 is smaller than when pads 10 are arranged in two rows. Since thespace occupied by pads 10 is smaller, it is possible to leave enoughspace to form wires different from pads 10, 11 a to 11 k, under bumpelectrodes 8 in the same layer in which the pads 10 lie. Therefore, thesemiconductor chip size can be further reduced. The wires 11 a to 11 kwhich are formed just beneath bump electrodes 8 need not be linear; theymay be folded or curved.

As mentioned above, one characteristic point of the present invention isthat a bump electrode 8 consists of a pad connection portion 8 a, awiring portion 8 b, and a terminal connection portion 8 c, and the padconnection portion 8 a and the terminal connection portion 8 c do notoverlap as seen in a plan view. The pad connection portion 8 a, wiringportion 8 b and terminal connection portion 8 c are in the same layer.This make it possible that bump electrodes 8, extending in the ydirection, are arranged in a zigzag pattern while pads 10 are arrangedin one row in the x direction. Since the terminal connection portion 8 cas a part of the bump electrode 8 is bonded to a packaging substratesuch as a glass substrate, its width is made larger than the width ofthe wiring portion 8 b and that of the pad connection portion 8 a inorder to ensure the required adhesive force. The characteristic point ofthis embodiment that a bump electrode 8 consists of a pad connectionportion 8 a, a wiring portion 8 b, and a terminal connection portion 8 cmay be interpreted as follows: a bump electrode 8 includes a narrowerwiring portion (first portion) 8 b and a terminal connection portion(second portion) 8 which is wider than the wiring portion 8 b. Thismakes it possible that the area of contact with the packaging substrateis sufficient and bump electrodes 8 are arranged in a zigzag pattern atsmall intervals. Stated another way, the terminal connection portion 8 cof a bump electrode 8 is relatively wide because the terminal connectionportion 8 c is to be bonded to a packaging substrate while the width ofthe wiring portion 8 b is relatively small because the wiring portion 8b is only intended to connect the pad connection portion and theterminal connection portion, so that bump electrodes 8 are arranged in azigzag pattern at small intervals.

According to the second embodiment, the positions of pads can bedetermined so as to reduce the semiconductor chip size efficientlyregardless of bump electrode positions. In other words, since greaterlatitude in pad arrangement is permitted, the semiconductor chip sizecan be reduced efficiently. In addition, since the area of the terminalconnection portion 8 c of a bump electrode 8 may be increased regardlessof the pad 10, the area of contact with the packaging substrate can bechanged flexibly.

The method of manufacturing a semiconductor device according to thesecond embodiment is almost the same as in the first embodiment. Thedifference is that a bump electrode 8 consists of a pad connectionportion 8 a, a wiring portion 8 b, and a terminal connection portion 8c, and the pad connection portion 8 a and the terminal connectionportion 8 c do not overlap as seen in a plan view. Furthermore, thewidth of the terminal connection portion 8 c should be larger than thatof the wiring portion 8 b. A semiconductor device according to thesecond embodiment is manufactured with these points into consideration.

Next, a variation of the second embodiment will be explained. FIG. 21 isa plan view of a variation of the second embodiment. FIG. 21 shows acase that pads 10 are arranged in one row in the x direction and theterminal connection portions 8 c of bump electrodes 8 are arranged inone row in the y direction. Even this variation can be realized by theuse of a bump electrode 8 which consists of a pad connection portion 8a, a wiring portion 8 b, and a terminal connection portion 8 c. Forexample, even when the terminal connection portions 8 c of bumpelectrodes 8 are arranged in one row in the y direction in order to meetthe customer's request, pads 10 can be arranged in one row in the xdirection. The positions of pads 10 can be determined irrespective ofwhere the terminal connection portions 8 c are formed. Again, though notshown in FIG. 21, wires different from pads 10 are formed just beneaththe bump electrodes 8 in the same layer in which the pads 10 lie.Therefore, space just beneath the bump electrodes 8 can be usedeffectively so that the semiconductor chip size is reduced. Furthermore,since this permits greater latitude in the layout arrangement of pads10, the semiconductor chip size can be further reduced by optimizing thepositions of pads 10. FIG. 21 indicates that the wiring portions 8 b ofthe bump electrodes 8 are bent at right angles; however, instead it isalso possible that they are curved.

FIG. 22 is a plan view showing another variation of the secondembodiment. FIG. 22 shows a case that pads 10 are arranged in one row inthe x direction and the terminal connection portions 8 c of bumpelectrodes 8 are arranged in a zigzag pattern in the y direction. Eventhis variation can be realized by the use of a bump electrode 8 whichconsists of a pad connection portion 8 a, a wiring portion 8 b, and aterminal connection portion 8 c. For example, even when the terminalconnection portions 8 c of bump electrodes 8 are arranged in a zigzagpattern in the y direction in order to meet the customer's request, pads10 can be arranged in one row in the x direction. The positions of pads10 can be determined irrespective of where the terminal connectionportions 8 c are formed. Again, though not shown in FIG. 22, wiresdifferent from pads 10 are formed just beneath the bump electrodes 8 inthe same layer in which the pads 10 lie. Therefore, space just beneaththe bump electrodes 8 can be used effectively so that the semiconductorchip size is reduced. Furthermore, since this permits greater latitudein the layout arrangement of pads 10, the semiconductor chip size can befurther reduced by optimizing the positions of pads 10.

The invention made by the present inventors has been so far explained indetail in reference to preferred embodiments thereof. However, theinvention is not limited thereto and it is obvious that these detailsmay be modified in various ways without departing from the spirit andscope thereof.

Although bump electrodes 8 and pads 10 are located along the four edgesof a semiconductor chip in the abovementioned embodiments, obviously theinvention is not limited thereto. For example, it is also possible thatpads 10 are located in the vicinities of the four edges of thesemiconductor chip and bump electrodes 8 extend to the center of thesemiconductor chip 1. Alternatively it is also possible that pads 10 arelocated in the center of the semiconductor chip 1 and bump electrodes 8extend to the four edges of the semiconductor chip 1.

In the description of the above embodiments, it is assumed that asemiconductor device is used as an LCD driver but the invention is notlimited thereto and may be applied to a wide range of semiconductordevices which have bump electrodes.

The present invention may be used widely in the semiconductormanufacturing industry.

What is claimed is:
 1. A display driver mounted on a glass substrate,comprising: a semiconductor substrate of rectangular shape having a pairof long edges and a pair of short edges; a first insulating film formedover the semiconductor substrate; a first pad electrode and a second padelectrode formed over the first insulating film, and each formed of aconductive layer; a first wiring and a second wiring formed over thefirst insulating film, the first and second wirings being formed in thesame layer as the first and second pad electrodes; a second insulatingfilm formed over the first pad electrode, the second pad electrode, thefirst wiring and the second wiring; first and second openings formed inthe second insulating film; a first bump electrode of rectangular shapeformed over the second insulating film and electrically connected to thefirst pad electrode via the first opening; a second bump electrode ofrectangular shape formed over the second insulating film andelectrically connected to the second pad electrode via the secondopening, wherein the glass substrate includes first and secondterminals, wherein the first and second bump electrodes are arranged ata first interval in a first direction which is along one of the longedges of the semiconductor substrate, wherein the first and second padelectrodes are arranged at a second interval in the first direction,wherein the first and second bump electrodes have a pair of short edgesand a pair of long edges, respectively, the pair of long edges extendingin a second direction which is along one of the pair of short edges ofthe semiconductor substrate, wherein both the first wiring and thesecond wiring are disposed to intersect with the pair of long edges ofthe first and second bump electrodes in a plan view, and disposed underthe first and second bump electrodes, wherein a width of the firstwiring in the second direction is larger than a width of the secondwiring in the second direction, wherein the first wiring is disposed ata position where is further from the first and second pad electrodes inthe second direction in a plan view in comparison with the secondwiring, and wherein the first and second bump electrodes areelectrically connected to the first and second terminals, respectively.2. A display driver according to claim 1, wherein the first wiring is apower supply wire.
 3. A display driver according to claim 2, wherein thesecond wiring is a dummy wire.
 4. A display driver according to claim 1,wherein a width of the first and second bump electrodes in the firstdirection is smaller than a width of the first and second pad electrodesin the first direction respectively, and wherein a width of the firstand second bump electrodes in the second direction is larger than awidth of the first and second pad electrodes in the second direction,respectively.
 5. A display driver according to claim 1, wherein thefirst and second bump electrodes are formed of a gold film,respectively.
 6. A display driver according to claim 1, wherein both thefirst wiring and the second wiring are formed in an uppermost wiringlayer.
 7. A display driver according to claim 1, wherein thesemiconductor substrate includes circuits which drive a liquid crystaldisplay.
 8. A display driver according to claim 1, wherein the first andsecond bump electrodes are connected to the first and second terminalsby an anisotropic conductive film, respectively.